for additional funding to enhance the MOP's ability to penetrate into rock, concrete and steel.

It's thought that the bomb's first target could be Iran's worst kep secret, a facility nestled in the mountains near the holy city of QOM.

David Blair at The Telegraph reports that work on the Great Salt Desert bunker began almost five years ago while under the watchful eye of western intelligence agencies. It didn't take long for them to decide that Tehran was building a deep underground plant to secretly enrich uranium.

Blair points out that not only did Iran fail to explain the need for secrecy, the Fordow facility holds only 3,000 centrifuges, not enough, he says, for a public power program, "but just enough to produce weapons-grade uranium for nuclear bombs."

To fill those 3,000 slots, Tehran started to transfer centrifuges from Natanz into Fordow — buried behind dozens of feet of mountain.

Massive bombs like the MOP are part of the U.S.'s initiative to decrease dependence on nuclear weapons as a deterrent.

Secretary of Defense Leon Panetta says Iran isn't the only potential target. "It's not just aimed at Iran. Frankly, it's aimed at any enemy that decides to locate in some kind of impenetrable location. The goal here is to be able to get at any enemy, anywhere."